Hot water vacuum extraction machines or vacuum cleaners generally incorporate a removable, recovery tank or dump bucket for separating the detergent-containing hot water from the airstream after pickup by a vacuum head at the end of the suction hose remote from the extraction machine. By incorporating a hydro-air filter within the recovery tank or dump bucket, with one end of the hydro-air filter immersed in water within the recovery tank, dirty air under vacuum pressure returning to the recovery tank from vacuum cleaner vacuum head mixes with the water, accumulating within the bucket or provided to the same, to filter out dirt particles. The dirt particles separate from the airstream and are retained by the water. The dirt-free airstream is released to a space defined by the top of the recovery tank and an overlying dome cover, above the level of water within the recovery tank. The dirt free airstream passes downwardly through a riser tube under suction pressure from a vacuum pump coupled to the lower end of the riser tube. The clean air escaping from the recovery tank and after passage through the suction pump is permitted to escape through openings within the hot water vacuum extraction machine casing to which the recovery tank is removably mounted.
Hydro-air filters or aqua filters are found within vacuum extraction machines exemplified by U.S. Pat. No. 4,078,908 issued Mar. 14, 1978 to R. Eugene Blackman and entitled "Dump Bucket for a Wet-Dry Vacuum System Having Improved Liquid Flow Characteristics:"; U.S. Pat. No. 4,083,705 issued Apr. 11, 1978 to Carl Parise et al and entitled "Dump Bucket for a Wet/Dry Vacuum System"; and U.S. Pat. No. 4,145,198 issued Mar. 20, 1979 to Thomas M. Laule and entitled "Hot Water Vacuum Extraction Machine with Submicron Size Particle Filter".
Such hot water vacuum extraction machines, whether used in a dry vacuum cleaner mode or wet vacuum cleaner mode, often include additional filters other than the hydro-air filter for separating the dirt from the wet or dry airstream entering the recovery tank dome to prevent dirt particles and droplets of water from passing to the vacuum pump and/or the electric motor driving the vacuum pump and which can contaminate those parts. Typically, a screen type filter is fixed to the inlet end of the riser tube to permit the return air to pass through the riser tube and out of the bottom of the recovery tank through a riser tube outlet port coupled by an air passage or duct within or beneath the bottom of the machine casing and opening to the suction side of the suction pump.
While the inlet opening to the riser tube is normally at a level well above the level of water within the tank to effect a hydro-air filter action for the return airstream carrying the dirt particles, overfilling of the recovery tank may occur with the water level rising dangerously close to the inlet port of the riser tube. Additionally, the incoming airstream tends to agitate the water accumulating within the bottom of the recovery tank or purposely prefilled therein, for effecting a hydro-air filter action, causing droplets of water to splash upwardly in the vicinity of the riser tube inlet port.
Attempts have been made to install baffles within the recovery tank between the water and the riser tube inlet port to reduce water splash and movement of water particles along the exterior of the user tube towards the riser tank inlet port. While such baffles and the like perform adequately, there is no guarantee that some water will not enter the riser tube and be sucked down into the vacuum pump or reach its electrical drive motor.
It is therefore a primary object of the present invention to provide a hot water vacuum extraction machine employing a hydro-air filter with a float sealed riser tube for automatically sealing off the inlet port to the riser tube as a result of predetermined volume of water accumulating within the recovery tank and to prevent water splashing into the open inlet port of the riser tube upon overfilling of the recovery tank with water.
It is a further object of this invention to provide a float sealed riser tube inlet port shut-off device which employs a float ball of a predetermined density normally maintained by gravity within a cage or cup to the side of the riser tube and below the level of the inlet port, which float ball upwardly by the rising level of water within the recovery tank, and which moves into the airstream entering the inlet port of riser tube where, such airstream causes the float ball to move rapidly into a position sealing off the inlet port to the riser tube well before the water level reaches the riser tube air inlet port, thereby preventing water from entering into the inlet port and reaching the vacuum pump.
It is a further object of the invention to provide a float ball integrated to a screen filter to a side of the riser tube for automatically closing off an air passage connecting the interior of the filter screen and constituting an inlet port of the riser tube and wherein, with the filter screen and its supporting structure acting as a cage for the float ball as well as means for shielding the float ball, in its normal gravity induced rest position at the bottom of the filter screen structure, from the air stream seeking the riser tube inlet port to thereby prevent premature movement of the float ball into a position sealing off that inlet port.